I recently installed Windows 7 on my laptop. I also configured IIS 7.5 on it, installed php 5.3.1 and MySQL 5.1.

Everything seemed to be installed correctly: I could see the IIS 7 Welcome screen, I could look at the php configuration with phpinfo() and I could see the MySQL tables using the MySQL Administrator GUI.

But when I tried to use phpMyAdmin, I got stuck: after trying to load the homepage of phpMyAdmin for 20-30 seconds, I got an HTTP Error 500. I searched the internet for hours, trying to find somebody with a similar experience, but I did not find any valuable resources.

Even a very simple test-script like

<?php
echo "#1. Try to connect to mysql server...";
mysql_connect("localhost", "username", "password") or die(mysql_error());
echo "Connected to MySQL<br />";
?>

generated a HTTP 500-error, after a 20-30 seconds wait.

Eventually, I decided to look at what I had installed when I was still using Vista. The difference seemed to be php: on my previous system, php 5.2.10 was installed.

I finally uninstalled MySQL and php 5.3.1, and then reinstalled php 5.2.11 and MySQL 5.1.41. That combination seemed to work without issues.

Conclusion: IIS 7.5 + php 5.3.1 + MySQL 5.1 does not seem to be a workable solution (for now). Stick to the 5.2-branch of php if you want to use it on Windows 7/IIS 7.5.